Fluid check for lifting-trucks



w. B. SIGVEL. FL'D CHECK FOR` LIFTINGTRUCKS.

APPLICATION FILED OCT. 4. 1917.

` Patented Deu. 20, 1921.

UNITED STATES PATENT OFFICE.

WILLIAM B. SIGEL, OF AMELIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS TOTHESTUEBING TRUCK CO., 0F CINCINNATI, OHIO, A CORPORATION OF OHIO.

FLUID CHECK FOB LIFTING-TRUCKB.

Specification of Letters Patent.

Patented Dec. 20, 1921.

Application led October 4, 1917. Serial No. 194,808.

:mism-is adapted to check and govern the downward movement ofthe liftingplatform of such trucks,keeping the same from falling suddenly or with'a thud, and the invention relates more particularly to means includedin said check mechanism to facilitate lower ing of the elevatingplatform into normal position when it is empty and unloaded or whenloaded.

The lifting platform, when raised, is usually locked in position, sothat the load can be moved to any point, and when it is desired to lowerthe loaded lifting platform, the locking parts are released. and thefluid check will allow the load to gradually fall with fthe platform, tonormal position.

When the lifting platform is 4not loaded or empty and is in an elevatedposition, and it is desired to lower the same, it is first unlockedfromI its elevated position and a spring used in connection with mycheck mechanism which is stressed when the lifting platform is elevated,acts to pull down said empty platform.

The salient feature of my invention oonsists in providing means inconnection with the fiuid check mechanism just above set forth, whichfunctions when the elevated or lifting platform is in a raised positionand empty, to cause the platform to `fall at a maximum speed, that is,reach its lowest or normal position quickly, to save time and preparequickly for reuse; but if the elevated or lifting platform is up andloaded this means will, upon the platform being released, cause the sameto descend slowly and uniformly and at a minimum speed so 'as not to 'arany of the parts.

n the accompanying drawing forming part of this specification:

Figurel, is a longitudinal 'sectional view of the fluid check cylinderwith certain parts in elevation; T

Fig. 2, is a section on line 2 2 of Fig. 1, part of the valve mechanismbeing broken away.

In the drawing, 52 designates the rear end of the check, which isadapted to be secured to a stationary portion of a lifting truck..

The rear end 52 of the check is attached to a cylinder 54 through oneend of which passes the piston rod 55. On the piston rod, at its rear,is attached a piston or piston head 56. This piston carries al washer oriston packing ring 57.

t one end of the piston is placed a disk valve 58, held against thepiston by spring 59, which spring is held in place by a washer held bypin 61. Through the piston extends passage ways 62, in the presentinstance three.- Thron h the valve 58 is placed a by-pass or b eedpassageyway 63, through which oil can pass into an annular recess 64 inthe piston into the space 71 in the cylinder in front of the piston,when the loaded or unloaded elevating platforml is lowered.

The piston rod 55 is to be attached to the lifting or elevating platformof a truck.

Around the piston rod 55 and between the piston 56 and the part or head65 is placed a coiling spring 70.

Assuming that the rear end 52 is connected to a stationary portion of alifting truck and the piston rod 55 is connected to the elevatingplatform of the truck, it will be apparent that when the elevatingplatform, with the load, is elevated, the piston rod will move outwardlyand cause the piston 56 to compress the spring 70.

When the elevating platform has reached its highest point it is lockedor held elevated 'so that the load can be carried todany point.

Vhen this elevating platform is released the stress on the spring 70 4isbroken and the spring relaxes and pulls down the elevating platform orgives it an initial impetus on its downward journey.

During this elevating operation of the lifting platform, the fluid oroil in space 71 is forced through the elongated passages 62 in piston 56into space 72, 1n the rear of the piston the force lifting valve 58 offits seat or away from the face of the piston, until the elevatingplatform has been locked or held in elevated position. At this time thespring 59 tends to force the disk valve 58 forwardly against the face ofthe piston '56.

yAs soon as the elevating .platform is rep time the lifting platform isin'lowered position again. The check device and mechanism just set forthis now in use and is disclosed in said patent to W. Stuebing, Jr.,

1 rests against said shoulder 8 1 in the wide and the lowering of theelevating platform whether loaded or unloaded is accomplished inapproximately the same amount of time. I will now specifically setAforth my improvements on the check above described.

In the piston 56, I provide a chamber 8O whichis of greater width at itsforward end than at itsrear end, and this chamber is providedintermediate its ends with a shoulder 81. A pin 82 lits in the narrowpart of said chamber 80 and its head 83 part. In the wide part of saidchamber 80, I arrange a headless screw 84 and between this screw and thehead 83 /of thepin 82 is arranged a coiled spring 85. i

It will be understood that when the lifting lplatform is in its lowestposition the piston and its parts' are in the rear end 72 of thecylinder 54 and the fluid is in the forward. end of the cylinder; when,and during the operation of raising the elevating platform, the fluid orliquid is forced through the holes 62 against valve 58, said disk valve58 is forced against spring 59 thus forming a passage 91 between theface of the piston 56 and said disk valve 58, to allow the fluid to passto the rear of the piston.-

Whenrthe elevating platform has been raised Vto its highest position thefluid is in `the rear end 72 of the cylinder and the platform is lockedin raised position'.

'In my improvement the valve disk 58 .through agency of pin 82 andspring 85 is'. held in va osition to allow the liquid to pass througlipiston 56 into the forward end 71 of chamber 54 when the platformis-lowering and when the pressure of the fluid against disk valve 58 isnormal or not stron enough to overcome the spring 85 and orce the pin 82flush with the face l of the piston. lIhis will allow the elevatingplatform, -lf empty, to `come down very rapidly and at the same timeautomatically.l When the pressure of the fluid in the rear 7 2 y of thecyl1nder is, however, great enough to overcome the spring 85, and this-is the case when the platform is loaded, the valve disk 58 is forcedagainst the face of the piston 56 closing the direct passage of thevthrough the by-pass 63 and recess 64.

ass

onits load will fall disk 58 jand causing the liquid to sequentlytheplatform and vcrvg slowly.

hat I claim as new and my invention and desire to secure by LettersPatent is:

l. A fluid check device for lifting trucks comprising a cylinder adaptedto be connected at one end to a fixed part of a truck, a piston in saidcylinder, a rod carried by said piston and extending through the otherendof the cylinder for connection with a movable part of the truck, saidiston having longitudinal openings therein, a tensioned valve on saidrod arranged adjacent the piston openings, one of said openings beingenlarged adjacent the inner end of the piston, a 1n within the `smallerbore of the last name opening and 2. A fluid check device includin acyl-V inder, a piston rod slidably mounte in said cylinder, a pistonmounted on said rod within the cylinder and provided with a iuidpassage-way to permit fluid to pass from one side of the piston to theother, a disk valve of less diameter than the piston slidably mounted onthe piston rod and adapted to seat against one end of the piston, saidvalve being provided with a by-pass to permit fluid to enter the iuidpassageway in the piston when the valve is seated against the piston,said piston being provided with a chamber, a pin mounted in said chamberand engaging said valve, and a spring arranged in the chamber andeny'said cylinder, a piston mounted on said rod within the cylinder, acoil spring surroundin'g the rod and arranged between the piston and theend of the cylinder through which the rod passes for normally 'forcing'said piston away from the -end. Vof the cylinder through which the rodpasses, a fluid passage-way provided in the piston and extending fromone of its ends to its other end to permit fluid in 'the cylinder topass' from one side of thepiston to the other side of the same, a diskvalve of less diameter than the iston slidably mounted on said piston'rodp and designed when seated against one end of the piston to preventthe direct ent of Huid from the cylinder into the end o the passagefwaywhich is varranged adjacent to said valve, a coil sprin arranged on thepiston rod for forcing sai valve toward the piston, said piston 'beingprovided at one of its ends with an annular recess which communicateswith said pasf sage-way, a Toy-pass arranged in the valve forintroducing fiuid intol said annular recess when the valve abuts againstone end of the piston, and a spring pressed pin slidably mounted in thepiston and having one of its ends engaging said piston for normallyholding the valve away from this piston to permit iuid in thecylinder topass betweenv the valve and piston direct into said uid passage-way.

In testimony whereof l aix my signa` ture in the presence of twowitnesses.

WILLIAM B. SIGEL

